The Black Cauldron by Lloyd Alexander
In the second of The Chronicles of Prydain, Taran, the Assistant Pig-Keeper, sets off on another quest to help Gwydion and other warriors to steal the black cauldron from Arawn and destroy it before Arawn can use it to create more invincible Cauldron-born warriors. He is joined again by the dwarf, Doli, the princess Eilonwy, Gurgi, and the bard Fflewddur Fflam. In this story, Taran has the opportunity to wear his first sword. He dreams of showing his mettle and being a hero, but once again things do not go as planned. He meets Ellidyr, the young prince with a thirst for fame, and Adaon, a valiant warrior who is both gentle and brave. If you enjoyed The Book of Three, you will enjoy this continuation of Taran’s adventures.